Sunday After Ascension Day
Augustine on Psalm CVIII
O GOD, the King of glory, who hast exalted thine only Son Jesus Christ with great triumph unto thy kingdom in heaven; We beseech thee, leave us not comfortless; but send to us thine Holy Ghost to comfort us, and exalt us unto the same place whither our Saviour Christ is gone before, who liveth and reigneth with thee and the same Holy Ghost, one God, world without end. Amen.
Source: Archbishop Cranmer [1549 AD]. The collect is based on the anthem that was sung on Ascension Day at Vespers "O King of Glory, Lord of Hosts, who today didst ascend in triumph far above all heavens, who did not leave us orpahns..." and John xiv "I will not leave you comfortless: I will come to you " [Barbee and Zahl]
Isaiah lxv. 17; 1 St. Peter iv. 7; Psalms 108, 110 | 46, 47 , & St. John xv. 26
Homiliy of Augustine on Psalm CVIII
Set up thyself, O God, above the heavens, and thy glory above all the earth;
Isaiah lxv. 17
For, behold, I create new heavens and a new earth: and the former shall not be remembered, nor come into mind. But be ye glad and rejoice for ever in that which I create: for, behold, I create Jerusalem a rejoicing, and her people a joy. And I will rejoice in Jerusalem, and joy in my people: and the voice of weeping shall be no more heard in her, nor the voice of crying. There shall be no more thence an infant of days, nor an old man that hath not filled his days: for the child shall die an hundred years old; but the sinner being an hundred years old shall be accursed. And they shall build houses, and inhabit them; and they shall plant vineyards, and eat the fruit of them. They shall not build, and another inhabit; they shall not plant, and another eat: for as the days of a tree are the days of my people, and mine elect shall long enjoy the work of their hands. They shall not labour in vain, nor bring forth for trouble; for they are the seed of the blessed of the LORD, and their offspring with them. And it shall come to pass, that before they call, I will answer; and while they are yet speaking, I will hear. The wolf and the lamb shall feed together, and the lion shall eat straw like the bullock: and dust shall be the serpent's meat. They shall not hurt nor destroy in all my holy mountain, saith the LORD.
Psalm 108, 110 | 46, 47
1 St. Peter iv. 7.
THE end of all things is at hand: be ye therefore sober, and watch unto prayer. And above all things have fervent charity among yourselves: for charity shall cover the multitude of sins. Use hospitality one to another without grudging. As every man hath received the gift, even so minister the same one to another, as good stewards of the manifold grace of God. If any man speak, let him speak as the oracles of God; if any man minister, let him do it as of the ability which God giveth: that God in all things may be glorified through Jesus Christ, to whom be praise and dominion for ever and ever. Amen.
St. John xv. 26, and part of Chap. xvi.
WHEN the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me: and ye also shall bear witness, because ye have been with me from the beginning. These things have I spoken unto you, that ye should not be offended. They shall put you out of the synagogues: yea, the time cometh, that whosoever killeth you will think that he doeth God service. And these things will they do unto you, because they have not known the Father, nor me. But these things have I told you, that when the time shall come, ye may remember that I told you of them.
1. I have not thoughte that the CVIIIth Psalm required an exposition; since I have already expounded it in the LVIIth Psalm,  and in the LXth, of the last divisions of which this Psalm consisteth. For the last part of the LVIIth is the first of this, as far as the verse, "Thy glory is above all the earth." Henceforth to the end, is the last part of the LXth: as the last part of the CXXXVth is the same as that of the CXVth,  from the verse, "The images of the heathen are but gold and silver:" as the XIVth and LIIId,  with a few alterations in the middle, have everything the same from the beginning to the end. Whatever slight differences therefore occur in this CVIIIth Psalm, compared with those two, of parts of which it is composed, are easy to understand; just as we find in the LVIIth,  "I will sing and give praise; awake, O my glory:" here," I will sing and give praise, with my glory."  Awake, is said there, that he may sing and give praise therewith. Also, there, "Thy mercy is great" (or, as some translate, "is lifted up") "unto the heavens;"  but here, "Thy mercy is great above the heavens."  For it is great unto the heavens, that it may be great in the heavens; and this is what he wished to express by "above the heavens." Also in the LXth, "I will rejoice, I will divide Shechem:"  here "I will be exalted, and will divide Shechem."  Where is shown what is signified in the division of Shechem, which it was prophesied should happen after the Lord's exaltation, and that this joy doth refer to that exaltation; so that He rejoiceth, because He is exalted. Whence he elsewhere saith, "Thou hast turned my heaviness into joy; Thou hast put off my sackcloth and girded me with gladness."  Also there "Ephraim, the strength of my head:"  but here, "Ephraim the taking up of my head."  But strength cometh from taking up, that is, He maketh men strong by taking up, causing fruit in us; for the interpretation of Ephraim is, bearing fruit. But "taking up" may be understood of us, when we take up Christ; or of Christ, when He, who is Head of the Church, taketh us up. And the words, "them that trouble us," in the former Psalm,  are the same with "our enemies," in this. 
2. We are taught by this Psalm, that those titles which seem to refer to history are most rightly understood prophetically, according to the object of the composition of the Psalms....And yet this Psalm is composed of the latter portions of two,  whose titles are different. Where it is signified that each concur in a common object, not in the surface of the history, but in the depth of prophecy, the objects of both being united in this one, the title of which is, "A Song or Psalm of David:"  resembling neither of the former titles, otherwise than in the word David. Since, "in many places, and in diverse manners," as the Epistle to the Hebrews saith, "God spoke in former times to the fathers through the Prophets;"  yet He spoke of Him whom He sent afterwards, that the words of the Prophets might be fulfilled: for "all the promises of God in Him are yea." 
Let us pray in the words of Augustine.
Turn we to the Lord God, the Father Almighty, and with pure hearts offer to him, so far as our meanness can, great and true thanks, with all our hearts praying his exceeding kindness, that of his good pleasure he would deign to hear our prayers, that by his Power he would drive out the enemy from our deeds and thoughts, that he would increase our faith, guide our understandings, give us spiritual thoughts, and lead us to his bliss, through Jesus Christ his Son our Lord, who liveth and reigneth with him, in the Unity of the Holy Spirit, one God, for ever and ever. Amen.
[A prayer which he was wont to use after his Sermons and Lectures.]
NPNF (V1-08) St. Augustine
Lat. CVII. Why no exposition is here given.  Ps. lvii. 8-12, lx. 5-12.  Ps. cxxxv. 15, cxv. 4.  Ps. liii.  Ps. lvii. 7, 8.  Ps. cviii. 1.  Ps. lvii. 10.  Ps. cviii. 4.  Ps. lx. 6.  Ps. cviii. 7.  Ps. xxx. 11.  Ps. lx. 7.  Ps. cviii. 8.  Ps. lx. 12.  Ps. cviii. 13.  Ps. lvii. Tit.; Ps. lx. Tit.  Ps. cviii. Tit.  Heb. i. 1.  2 Cor. i. 20.